What's odd is the blue ink isn't visible in all photos. Also odd—if the blue is there, as in the second one—the date/place are clearly in a different hand. Why do that—if you're faking writing? Adding "D.A." would also be a risk unless he was known to do it. But: yes, concerning.
2/ Right now FNC is only reporting that the date and location were added; when I looked, I didn't see anything about a last name and "D.A."—which would be much, much bigger news. Given Allred is offering handwriting analysis, I think she's confident on the "Moore, D.A." part too.
3/ But yes, if it turned out "Moore" and "D.A." were written by a different person, it'd be a problem—I just don't think anyone's reporting that, nor (if they did) would it explain why a "forger" would change their handwriting in midstream. I've never seen that in a forgery case.
4/ If the handwriting analysis of "Moore D.A." checks out—as Allred says it will—it would suggest what happened is Moore had to switch pens to finish his inscription and Nelson then coincidentally added the date/place (but note—deliberately *in a different hand*) with a blue pen.
